RSO from Iso is heavy in chlorophyll, which gives some folks gastric upset in concentration, in the form of cramps, diarrhea, and vomiting. Naphtha ISO has little chlorophyll, but is heavy in waxes and us often poorly purged.
Naphtha only specifies a boiling point, not what is in it, and frequently contains Benzene, a known carcinogen. Rick and I've discussed that issue, even on national radio, but he has been this far unmoved to stop specifying naphtha, and believes it has properties unlike anything else.
One theory is that the residual naphtha ties up the liver and allows the cannabinoids to last longer, but residual naphtha poisonings have also been reported.
To me, the name RSO oil, specifies oil that has been extracted using naphtha and a rice cooker, using Ricks published methods. I salute Rick for what he did to advance medical cannabis, but reject his methods as archaic even dangerous, from the standpoint of the solvent he specifies and his purging process for adequately removing residuals.
To dispel any personal biases, opinions, or secondary motives from the formula, I extracted one lot of Blue Dream using five different solvents, including Naphtha. I ran GC analysis in our own lab, and turned the samples over to a third party full blown analytical lab for testing, to show what the different solvents extract from the same material. More on that, when the lab sends the results.